The coastal tiles are .dds 3 type, and are blended toward the edges.
Guessing I would have to make all the land tiles type 3 and give them some transparency?

Still wouldn't look right, they would appear dim.

Had a look in the PlanetTexture documentation:

Quote:

4.2 The Mask layer The Mask layer contains the planet water mask (for rendering specular reflection of water surfaces) and the night light texture, if applicable, in a combined 512512 pixel DXT1 texture file (1-bit transparency). The RGB channels of the texture provide the night light information, while the 1-bit alpha channel provides the water mask (alpha=0: water, alpha=1: land). Due to a limitation of the DXT1 format, pixels with alpha=0 do not contain RGB information. Therefore, night lights cannot be defined on water surfaces. A planet with neither night lights nor specular reflection surfaces does not need to provide a Mask layer.

Guessing its not possible? The Mask layer is working properly, just being covered by my new surface tiles?

What might work is making the land tiles type 1, so they have a 1 bit transparency. Then using the mask layer to "punch" a hole in the surface tile.
Would have to find and match the relevant piece of the Mask Layer to each surface tile.
As there are over a hundred, probably won't happen.